Airplane propeller



June 29, 1943. w, MAR INO 2,322,763

AIRPLANE PROPELLER Filed Jan. 8, 1940 F Y-2Q Fig-.

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' "an" 1 H! Patented June 29, 1943 UNITED STATES PATENT OFFICE AIRPLANE PROPELLER William Martino, Detroit, Mich.

Application January 8, 1940, Serial No. 313,000

7 Claims. (Cl. 170-159) My invention relates to new anduseful improvements in aircraft propeller construction.

An important object of my invention is the provision of an aircraft propeller that is unique in its construction to substantially reduce the vacuum that normally manifests itself rearwardly of the shank and hub portion of the propeller assembly.

Another object of my invention is the provision of an aircraft propeller wherein freely rotatable sleeves are associated with the shank portion of the blade of the propeller. in a manner whereby rotation of the propeller will effect the rotation of the sleeves and the rotation of the sleeves will in turn agitate the air circumjacent assembly that is light in weight and that may be easily and expeditiously applied to the propeller. Other objects and advantages of my invention,

will be apparent during the course of the follow ing description. In the drawing, forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Figure l is a front elevation of a propeller assembly showing parts broken away, and illustrat- 1118 a device embodying my invention incorporated therewith,

Figure 2 is a fragmentary longitudinal sectional view, taken on the line 2--2 of Figure 1,

Figure 3 is a transverse sectional view, taken on the line 3-3 of Figure 2,

Figure 4 is a fragmentary front elevation of a modified form of my invention,

Figure 5 is a transverse sectional view, taken on-the line H of Figure 4, and

Figure 6 is a front elevation of another modification of the invention.

In the accompanying drawing, wherein for the purpose of illustration is shown a preferred embodiment of my invention, the numeral l0 designates a propeller assembly including a hub portion II and radially disposed blades i2 formed with a cylindrical shank portion i3 at the Juncture thereof with the hub. The propeller blades secured to the split sleeve i'l adjacent the end thereof and the companion band or strap I! is hingedly associated therewith, as at 20. The free ends of the bands It and I! are formed with radially extending flanges 2| and 22 normally spaced slightly apart and provided with alignin is desired to adjust the pitch of the prop the nut 24 may be loosened and when the propeller has been made to assume the desired angle, the nut may be tightened to securely hold the blade against displacement.

The following description is directed to but one of the propeller blade constructions; however, it is to be understood that each of the propellers are of identical construction and that the description may be applied to all of the blades.

The shank portion i3 of the blade is of lesser diameter than either the butt end It or the adjacent portion 25 to define annular shoulders '23 and 21 at its respective ends. The tubular sleeve 28 enclosing the shank is supported at its opposite ends by ball bearings 28 and 30, and the outer end ii of the sleeve is provided with a thrust bearing 32 to support the sleeve against the centrifugal force effected during the rotation of the propeller. The thrust bearing 32 is seated against the shoulder 21 of the propeller blade and the ball bearing 30 is disposed in abutting relation therewith and held against displacement by the inner annular bead 33. The bearing 29 is similarly held in abutting relation with the shoulare associated with the hub in the conventional der 26 by the inner annular head 34. In the form of the invention, as illustrated in Figures 1, 2 and 3, the sleeve 23 is formed with a plurality of spaced radially extending, helically disposed ribs or webs II.

The bearings have here been described as comprising the type generally designated as ball bearings; however, it is to be understood that roller bearings, or the like, may be substituted therefor if desired.

The eflective working face of the propeller during rotation comprises substantially the outer two-thirds thereof. The hub portion and the portion of the blade adjacent to the hub in no way aid in the effective working action of the propeller and, in fact, materially decrease the efficiency of the propeller by increasing the resistance between the propeller blade and the circumjacent atmosphere. The applicant's invention is adapted to materially aid the travel of the propeller blade through the air and to substantially reduce the vacuum which normally tends to, manifest itself rearwardly of the hub and shank portions of the propeller blades. The rotation of the propeller will cause a blast of air to be impinged against the radially extending ribs 38 of the sleeves and thereby effect the rapid In the form of the invention, as illustrated in Figures 4 and 5, the sleeves 28 are formed with a plurality of spaced helically disposed concavities or pockets 36. The purpose of the pockets is substantially the same as that set forth in connection with the helically disposed webs 35 described in relation to the first form of the invention. The rotation of the propeller will cause a blast of air to be impinged against thesleeve and into the pockets which by virtue of the helical disposition thereof will effect rapid rotation of the sleeve to facilitate the passage of this portion of the propeller through the air and to agitate the atmosphere therearound. .The results achieved by this form of the invention are believed to be so similar to those described in relation with the first form that no further explanation is thought to be necessary.

In the form of the invention as illustrated in Figure 6, means is provided to effect a positive drive for the sleeves. The stationary beveled ring gear 31 is bolted, or otherwise secured, to the forward end of the crankcase of the motor in a manner whereby the teeth of the same will' be disposed laterally of the inner ends of the sleeves 28. The beveled gears 38 are carried by the inner ends of the sleeves and with their teeth in meshed relation with the teeth of the ring gear, whereby rotation of the propeller will cause the blast of air created by rotation of the propeller is directed thereagainst whereby to agitate the air around the shanks and to thereby destroy the vacuum normally existent at the trailing edge thereof.

3. An aircraft propeller having, in-combina-' tion, sleeves mounted for axial'rotation about that portion of the propeller blades which is in close proximity to the hub portion thereof, said sleeves having radial ribs disposed helically therearound whereby rotation of the propeller will effect rotation of the sleeves and whereby the action of the ribs against the air around the axial rotation about that portion of the propeller the beveled gears to traverse the ring gear and f;

to eflect a rapid rotation of the sleeves.

While the gears 38 have been here illustrated as being applied to the first form of the invention, as shown in Figures 1, 2 and 3, it is to be understood thatthey may be easily adapted to blades which is in close proximity to the hub portion thereof, said sleeves having helicoidal formations on their outer surfaces adapted to effect the rotation of the sleeves when the blast of air created by rotation of the propeller is di-. rected thereagainst whereby to agitate the air around the shanks and to thereby destroy the vacuum normally existent at the trailing edge thereof.

5. In combination with an aircraft propeller assembly including a hub and radially disposed blades having cylindrical shank portions adjacent the said hub, sleeves mounted for free axial --rotation on the shank portions of the blades, and

fins projecting radially from the outer surface of the sleeves to effect rotation of the sleeves when the blast ofair created by rotation of the propeller is directed thereagainst whereby to agitate the air around the shanks and to thereby destroy the vacuum normally existent at the trailing edge thereof.

6. In combination with an aircraft propeller assembly including a hub having a'plurality of radially extending blades rotatably mounted thereon, each of the said'blades having a shank portion adjacent the hub, a sleeve mounted for rotation about the axes of each of the said shank portions, the surface of each of the said sleeves being formed with a plurality of spaced helically be taken as a preferred example of the same, 2"

and that various changes in the size, shape and arrangement of parts may be resorted to without departing .from the spirit of my invention, or scope of the appended claims.

Having thus described my invention, I claim; *5

' blades rotatably associated w th the hub, each 1. In combination with a propeller, sleeves loosely mounted for independent axial rotation about the propeller blade shanks in close proximity to the hub portion thereof, and means to be acted upon by the medium through which the propeller is moving carried by the sleeves foreffecting the rotation of the said sleeves, whereby,

being pitted to eifect rotation of the sleeves whenthe trailing edge of the innerthe air around the shank portions of the blades.

so as to destroy the vacuum normally existent at the trailing edge thereof.

' 7. In combination with an aircraft propeller assembly including a hub and radially extending of the said blades having a shank portion adjacent the hub, bearings mounted at the opposed end portions of the said shank portions, a sleeve mounted exteriorly of the said bearings for rotation about the axes of each shank portion, the outer surface of each sleeve having radially disposed ribs arranged helically thereof so as to effect rotation of the sleeves when they are moved through the atmosphere during turning of the propeller whereby to agitate the atmosphere so as to destroy the vacuum normally existent at shank portion of each propeller blade.

' WILLIAM MARTINO. 

